The present invention relates to a magnetic recording/reproduction apparatus for reproducing signals recorded on a high-density magnetic recording medium.
Some recent magnetic recording apparatuses use a vertical magnetic recording scheme which is particularly effective for high-density recording. Signals reproduced from a magnetic recording medium using the vertical magnetic recording scheme are 90 degrees out of phase with respect to those reproduced from a medium using a conventional inplane (longitudinal) magnetic recording scheme.
Referring to FIG. 1A, when 1-bit data (magnetic inversion) is recorded as a sine wave on a recording medium by the vertical magnetic recording scheme, a reproduced output signal obtained by residual magnetization is represented in FIG. 1B as E1. When, on the other hand, 1-bit data is recorded as a sine wave by the inplane magnetic recording system, its reproduced signal, E2 in FIG. 1C, is found, as shown in FIG. 1D, to be 90 degrees out of phase with signal E1.
As shown in FIG. 2A, when 1-bit data is recorded as a complete rectangular wave by the vertical magnetic recording scheme, reproduced output signal E3, shown in FIG. 2B, is obtained. When 1-bit data is recorded by the inplane magnetic recording scheme, as shown in FIG. 2C, reproduced output signal E4, shown in FIG. 2D, is obtained.
When 1-bit data is recorded as a rectangular wave by the vertical magnetic recording scheme and the recording medium is demagnetized, as shown in FIG. 3A, reproduced output signal E5, shown in FIG. 3B is obtained.
When 1-bit data is recorded as a rectangular wave by the in-plane magnetic recording scheme, and the recording medium is demagnetized as shown in FIG. 3C, reproduced output signal E6 shown in FIG. 3D, is obtained.
A magnetic recording/reproduction apparatus using the vertical magnetic recording must be able to reproduce information from a recording medium using the in-plane magnetic recording if highly efficient information processing is to be achieved.
Since reproduced output signals corresponding to the two schemes are 90 degrees out of phase, a conventional magnetic recording/reproduction apparatus using the vertical magnetic recording cannot reproduce information recorded by the in-plane magnetic recording. The residual magnetization transition point in a 1-bit data recording medium corresponds to the zero-cross point of the output signal reproduced in the vertical magnetic recording scheme and to the peak point of the output signal reproduced in the in-plane magnetic recording scheme.
A combination of the vertical magnetic recording scheme and the in-plane magnetic recording scheme is known. In this combination scheme, recording medium residual magnetization consists of vertical and in-plane componenets. With a recording medium having a residual magnetization in which the in-plane component is larger than the vertical component shown in FIG. 4A, an output wave shown in FIG. 4B is obtained. With a recording medium having a residual magnetization in which the vertical component is larger than the in-plane component shown in FIG. 4C, an output waveform shown in FIG. 4D is obtained. A magnetic recording/reproduction apparatus using the vertical magnetic recording scheme cannot reproduce such data.